Rust-resistant plated article



Patented Dec. 9, 1924.

UNITED STATES PATENT OFFICE.

CHRISTIAN JOHN WERNLUND, OF TOTTENVILLE, NEW YORK, ASSIGNO'R TO THEROESSLER & HASSLACHER CHEMICAL COMPANY, OF NEW YORK, N. Y., A CORPORA-TION OF NEW YORK.

RUST-RESISTANT PLATED ARTICLE.

No Drawing.

To all whom it may concern:

Be it known that I, CHRISTIAN JOHN WERNLUND, a citizen of the UnitedStates, and resident of Tottenville, in the county of Richmond and Stateof New York, have" invented certain new and useful Improvements inRust-Resistant Plated Articles, of which the following is aspecification.

My invention relates in general to the electroplating on iron and steelor other metal articles of alloys with zinc of metals having a highersolution potential .than iron, such as cadmium.

Cadmium has many properties which render it advantageous overothermetals and alloys as a protective coating for metals such as iron andsteel. It is light in color and has a higher solution potential thaniron, thus tending to protect the iron from corrosion. As its solutionpotential is higher than that of iron and lower than that of zinc, thesame weight of protective coating of cadmium affords more protection toatmospheric corrosion than is afforded by straight zinc. Also morecadmium than zinc can be deposited per unit of current used. The oxidecoating formed by atmospheric or other corrosion of cadmium is thinnerand more adherent than that formed on zinc, consequently the tendency ofcadmium to scale off and Waste away is much less pronounced than that ofzinc.

While I have found that pure cadmium coatings can be effectivelydeposited electrolytically, I have further found that alloy coatingscomprising cadmium retain in large measure the advantageous features ofpure cadmium coatings in durability and rapidity of deposit and can bemuch more cheaply and conveniently produced than previous coatings ofpure cadmium. Ac-' cording to my invention, I produce alloyed coatingscomprising cadmium and another metal, such as cadmium and mercury orzinc, or zinc cadmium and mercury, using either plain anodes with asuitable bath, or alloy anodes, or both. The coatings have the enhancedpractical advantages characteristic.

of pure cadmium coatings in .giving better Appllication filed January 5.1924. Serial No. 684,507.

protection than zinc with less thickness, good color of coating, andeconomy of current. The advantage of using mercury in combination withcadmium or zinc and cadmium is that the resultant coatingis moreresistant to corrosion than cadmium or zinc alone. The cathode potentialis raised with consequent increased throwing power.

Such a coating may be formed by the use of a plating solution to whichthe proper addition of cadmium or cadmium and mercury compounds solublein the bath have been made, or the metals can be furnished to thesolution by the use of cadmium anodes and zinc anodes or alloy anodes.If mercury is not desired in the final product a binary anode of zincand cadmium can be used.

Examples of the scope of this invention are as follows:

Ewample I.

Water 1 L. 1 gal. Sodium cyanide 60 G. 8 oz. Sodium hydroxide 15 G. 2oz. Cadmium hydrate 15 Gr. 2 oz. Mercuric oxide 0.1 G. 0.0125 oz.

Other conditions maintained are as follows:

Anodes Cadmium. Temperature 25 C. (77 F.)

E. M. F 3 to 6 volts. Current 15 amperes per sq. ft.

An average analysis of the coating produced will show cadmium 98-99% andmercury 1-2%.

The various ingredients of the bath must be replenished from time totime as they become depleted.

Ercample H.

Emamplc I l l To plate wire screen with-a zinc cadmium alloy, thematerial is cleaned by an alkaline electric cleaner or when rusty byalternate acid and alkaline pickling until a chemically clean metallicsurface is secured. The wire may then be plated in the followingsolution:

Water 1 gal. Sodium cyanide 45 G. 0 oz. Sodium hydroxides 30 G. 4 07..Zinc cyanide 30 G. 4 oz. Cadmium hydrate 7 .5 G. 1 oz.

Other conditionsmaintained are as follows:

Temperature 25 C. (77 F.)

E. M. F. 3 to 6 volts.

-Current 25 amperes per sq.- ft. Anodes zinc.

The bath must be replenished from time to time as the severalingredient-s become depleted. 'An average analysis of the resultingcoating will be zinc -75%, cadmium 25-30%.

Example IV.

I- have also found that the zinc and cadmium contents of the bath may bestabilized byusing zinc cadmium alloy anodes to supply the desirequantities of these metals to the solution. A preferred com' position ofsuch an alloy anode is zinc cadmium 25%.

In plating, for example, wire screen, I proceed as in Example III withthe exception that in this case I substitute the zinc cadmium in placeof the straight zinc anodes.

Example V.

' To plate steel casters with a zinc cadmium mercury alloy, they arecleaned by one of the alternative methods given in Example III dependingupon their'condition. When a chemically clean surface has been obtained,they maybe plated in the following solution:

Water 1 L. 1 gal.

Sodium cyanide 45 Gr. 6 oz.

Sodium hydroxide--- 30 G. 4 oz.

Zinc cyanide 30 G. 4 oz.

Cadmium hydra-ten- 7.5 G. 1 oz.

Mercuric oxide 0.1 G. 0.0125 oz.

Other conditions maintained are as fol-- lows:

Temperature 40 C.

E. M. F." 3 to 6 volts.

Current 25 amperes per sq. ft.

Anodes zinc.

The bath must be replenished from time to time as the severalingredients become de-- pleted. An average analysis of the coatingobtained is zinc 70-80%, cadmium 2030%, mercury 12%.

Example VI.

I have also found that the zinc. cadmium and mercury contents of thebath may be stabilized by using zinc cadmium mercury alloy anodes tosupply the desired quanti ties of these metals to the solution. Apreferred composition of such an alloy anode is zinc 73%, cadmium 25%,mercury 2%.

In plating, for example, steel casters I proceed as in Example V, withthe exception that in this case. I substitute the zinc cadmium mercuryin place of the straight zinc anodes. A coating of similar analysis tothat in Example V is obtained.

For some purposes, I have used a zinc cadmium mercury alloy anode of thefollowing composition: zinc 93%, cadmium 5%, mercury 2%.

In Examples III, IV, V, and VI, I have described methods of depositincoatings containing zinc and cadmium with and without mercury and inwhich zinc is the major constituent. ingsinvolving economy of rawmaterials. If desired, alloy coatings can be deposited whose majorconstituent is cadmium without departing from the spirit of thisinvention.'

In all they above examples the plating has been done in a still bath.Itis understood that if mechanical solutions are used such as in barrelplatin the concentrations of solutions, .currents required, etc. may bechanged considerably to conform to the dif-. ferent operatingconditions.

The elimination 'of anv single component of the ternary alloy describedabove and in the following claims gives a binary alloy deposit eithersuperior to straight zinc deposits or cheaper than straight cadmium.

These are the best coat- What I claim I 1. Asa new article ofmanufacture, a ferrous article having an electrolytic coating comprisingzinc together with 2% or more of cadmium.

2. As a new article of manufacture, a ferrous article having anelectrolytic coating comprising zinc, 2% or more of cadmium, and anothermetal having a solution potential lower than that of iron.

3. As a new article of manufacture. a fer. rous article having anelectrolvtic coating comprising zinc and more than 2% of an other metalhaving a solution potential higher than that of iron.

4. As a new article of manufacture. a ferrous article having an'electrolvtic coating comprising cadmium and zinc as major constitutentsand mercury as a minor constituent.

5. As a new article of manufacture, a ferrous article having anelectrolytic coating comprising cadmium from 2-30% and zinc from 70-98%.6. As a new article of manufacture, a-ferrous article having anelectrolvtic coating comprising cadmium from 2-30%, zinc from 70-97%,and mercury from 1-2%.

7. As a new article of manufacture. a ferrous article having anelectrolvticcoating comprising cadmium and mercury, cadmium bemg a ma orconstituent.

8. Asa new article of manufacture, a

' higher than that of iron.

28th day 9. As. a, new article of manufacture, a

metal article, having an electrolyticcoating camprising 2% or more ofcadmium, zinc,-

and another metal having a solution-potential lower than that of iron.

10. As a new article --of manufacture, a metal article, having anelectrolyticcoating comprising zinc and more than. 2% of another metalhaving a' solution potential 11.- As a new article of manufacture, ametal article having an electrolvtic coating comprising 2% or more ofcadmium, to-

gether with 'zinc and mercury.

.12. Asa new article of manufacture, a

metal article, having ail-electrolytic coating comprising cadmium 230% and zinc from 70-98%. r

- 13. As a he article of manufacture,-a metal article having anelectrolytic coating comprising. cadmium from 2-30%, zinc from 7 097'%,-and mercury from 1-2%.

14. As a new articleof manufacture,- a

metal article having an electrolvticfcoating.

comprising cadmium and mercury, cadmium being a ma or constituent.

Signed at Perth of Middlesex and State of New J ersev.

of December,fA. 1)., 1923.

HRISTIAN JOHN WERNLUND.

this

Amboy, in" the" county I I

